<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="d1">这是div</div>
<h2 class="c1">这是h2</h2>
<p class="c1">这是p</p>
<span class="c1">这是span</span>

<input type="button"value="获取"onclick="fn()">
<input type="button"value="修改" onclick="fn2()">
<input type="button"value="获取多个" onclick="fn3()">

<script>
    function fn3() {
let arr=document.getElementsByClassName("c1");
for (let i=0;i<arr.length;i++){
    let o=arr[i];
    o.innerText="我是c1";
}
    }
    function fn1() {
//得到div对象
        let d=document.getElementById("d1");
        //弹出div里面的文本
        alert(d.innerText);
    }
    function fn2() {
let d=document.getElementById("d1");
d.innerText="内容被修改了";
    }


</script>


</body>
</html>